Conventionally available as an X-ray detector installed in an X-ray computed-tomography (CT) apparatus is one including an arrangement of a plurality of X-ray detector modules. Each of the X-ray detector modules included in such an X-ray detector has, for example, a detection surface on which a plurality of detection elements detecting X-rays are arrayed at predetermined positions, and the X-ray detector modules are fixed to a frame with their detection surfaces aligned in a predetermined direction. With such a structure of the X-ray detector, each of the X-ray detector modules is fixed to the frame by accessing from the side of the detection surface, for example.
Generally speaking, in the X-ray detector installed in an X-ray CT apparatus, the detection surfaces of the X-ray detector modules are covered by a douser in order to suppress the light incident on the detection elements. Therefore, in a structure in which each of the X-ray detector modules are fixed by accessing from the side of the detection surface, for example, the douser needs to be removed in order to replace an X-ray detector module, which may cause the serviceability to be quite low.